I think this would be a perfectly reasonable place to randomly start reading, as it’s beginning a new mini-arc within the overall arc of story. This Mediterranean cruise is supposed to be a single parenthetic episode in Jack’s career—of course, things never work out the way people expect, and in these books least of all.

Jack’s interaction with Wray at cards at the beginning of Desolation Island sets off a plot that will not be fully resolved until the end of The Commodore, but there is also a voyage begun in Desolation Island which is ended in The Surgeon’s Mate. There’s also a plot that begins in Post Captain where Jack and Stephen meet Sophie and Diana, which you might think was also resolved in The Surgeon’s Mate when Stephen and Diana marry, except that O’Brian wasn’t done with it.

The Ionian Mission begins in London several months at least after the end of The Surgeon’s Mate, with Stephen and Diana on good terms but living apart because of his undomestic nature. Jack hasn’t been given the Acasta, because of Wray’s spite, and instead he’s sent to the Mediterranean in the Worcester, one of the “Forty Thieves,” a 70 gun but barely seaworthy ship of the line. They join the Mediterranean blocade of the French ports, hoping the French will come out and there will be a battle. Later when the Worcester becomes entirely unseaworthy after chasing the French, Jack is given his old command the Surprise for a detached mission in the Ionian in which he has to deal with contenders for the Albanian statelets of Marga and Kutali.

Now we’re back to the form of earlier in the series, starting out in England for a commission—and this commission will take us three books. Jack’s affairs in England are hopelessly muddled and he’s penniless again, because of his silver mine.

The book is enlivened with duelling poets—Mowett is joined by Rowan. It’s also enlivened by the presence of the ponderous Dr. Graham, who is spying for some other British agency. He gets entangled with Stephen on several occasions—it’s hilarious when Stephen tries to explain nautical jargon to him and gets carried away, but not so funny when he ruins a plan ashore in Catalonia.

One of my favourite moments is when Pullings presses a man who had been to sea as a boy and whose business will now be ruined, and Stephen tells him he’s not medically fit and lets him go. The whole thing doesn’t take more than a page, but it’s beautifully timed—and a rare instance of humanity in the Navy. I also very much like Jack messing up the diplomacy by agreeing right away, and I like the Englishman on the Turkish ship showing off about the marble cannonballs.

I always think of The Ionian Mission as being the first half of Treason’s Harbour, as if these two books were a pair within the series. It’s hard to remember where one stops and the other starts.

There are a lot of old friends here—Pullings and Mowett, of course, Babbington, with his own ship, the Dryad, Killick and Bonden. We see some old enemies too, Harte and Wray in particular. And Wray is closely connected to Harte, his son in law, as well as being highly placed at the Treasury. Harte is mean-spirited and hates Jack, but Wray is much worse.

The book ends abruptly, after the battle with the Torgud, without detail of the taking of Kutali, which surprised me the first time I read it, as we’d had so much lead up to that.

Jo Walton is a science fiction and fantasy writer. She’s published two poetry collections and eight novels, most recently Lifelode. She has a ninth novel coming out in January, Among Others, and if you liked this post you will like it. She reads a lot, and blogs about it here regularly. She comes from Wales but lives in Montreal where the food and books are more varied.